What does the word "impressive" mean when it comes to most impressive winning streaks?

Longevity.

Simply put, it's one thing to put together a bunch of wins. It is a great accomplishment and one for the record books, for sure. Take for instance Guillermo Vilas' 46 wins in a row in 1977, despite its controversial end or Martina Navratilova's even more amazing 74 victories in 1984, which RealClearSports labels as an unbreakable streak.

But that's not what is being covered here. The biggest criteria for this category is the ability to win, and win, and win over a long period of time.

Not just in 1977 or in 1984.

For that matter, not in any one year of the Novak Djokovic, Roger Federer, Rafael Nadal era of "just who is the Greatest of All Time?" Note that for sensitive readers, this G.O.A.T. list is alphabetized. No favorites here.

What follows is a ranking of the most impressive winning streaks in tennis history, with a men's and women's representative for each one.

No. 5: Most Consecutive Titles Won

What is intriguing about the statistic of consecutive titles won is that there are actually four winners here, three men and one woman. But they are all equally impressive.

Bjorn Borg, Ivan Lendl and John McEnroe each won eight straight titles while they were on tour.

Borg's streak began in November 1979, in Tokyo, where he defeated Jimmy Connors, 6-2, 6-2. Then he won titles in Canada, New York City, Boca Raton, Fla., Maryland, Nice, France, Monte Carlo and Las Vegas. It was May 1980 before he lost.

Lendl's eight started in 1981 in Madrid, Spain, on clay. He beat Pablo Arraya in straight sets, 6-3, 6-3, 6-2 (yes, a best-of-five match outside of a Grand Slam). It only ended after four clay, three hard, and one carpet titles were under his belt.

The only thing that could have made this run more memorable would have been a major title.

1984 saw John McEnroe start his streak with such a win. He beat Lendl, 6-3, 6-4, 6-1, at the U.S. Open. John Vilanova of Hamptons Magazinedescribed that victory as a "demolition." He would beat Lendl again, at the Masters final in New York City before finally losing in the quarterfinals of Dallas.

On the women's side, there is no such competition. Martina Navratilova reigns supreme when it comes to winning tournaments.

She ran off 13 straight championships from February 1984 to November 1984. Her winning streak included the French Open, Wimbledon and U.S. Open. She only lost five sets total among all of those appearances.

No. 4: Most Consecutive Titles at One Tournament

Some tournaments are nearly synonymous with certain players, and vice versa. Rafael Nadal and Martina Navratilova found even more success than normal for their careers at their favorite locations.

This category is more impressive than the previous because it takes place over years, not just a year or two. Longevity is the deciding factor.

Nadal has played his best tennis on clay. It is no surprise, then, that he has wowed his fans over a long period of time at a dirt venue.

Or make that two dirt venues.

Eight straight times, Nadal triumphed at Monte Carlo's Masters 1000 tournament and Barcelona's tourney. In the former he held the trophy aloft from 2005-2012 while he won the latter from 2005-2013 (skipping 2010)...and counting. These kind of winning streaks led James Buddell of ATPWorldTour.com to call the Monte Carlo record a "dynasty."

Much earlier, Navratilova dominated the Chicago stop on the women's tour. In 1978, she beat Evonne Goolagong Cawley in a tense three-setter, 6-7, 6-2, 6-2.

She won the next eight finals in straight sets, earning her a key to the city.

No. 3: Most Consecutive Wins at a Single Grand Slam

Mike Hewitt/Getty ImagesRoger Federer is a blur as he launches for a signature overhead, Wimbledon.

Having a favorite tournament and winning it often excites the local fans. When that tournament is a Grand Slam, it excites fans across the entire sport.

That's exactly what Roger Federer, Bjorn Borg and Martina Navratilova did for tennis.

All other things being equal, winning tournaments over the years is more impressive when it includes majors.

Federer partook of five straight victories at both Wimbledon and the U.S. Open. Those particular tournament runs, coming on two different surfaces, must stand above the accomplishment of Borg, who managed five straight titles at the All England Club.

In addition to the multi-surface accomplishment, there is the deciding factor of just how those finals were won.

Three of the Swede's wins came by way of five-setters.

In contrast, only one of Federer's 10 Grand Slam finals in New York and London went to five sets: the 2007 win over No. 2 Rafael Nadal. The Swiss eventually won, 7-6 (7), 4-6, 7-6 (2), 2-6, 6-2.

He won 30 out of 36 total sets in his title clashes.

Navratilova, again, sets the standard among women's players. For over half-a-decade, she won the Wimbledon Championships, dispatching American favorite Chris Evert four times. Her lefty serve carved out holes in the grass, opening up the whole court for her volleys.

No. 2: Most Consecutive Tour Finals Won

Each year, the World Tour Finals for men's and women's tennis crown the ultimate player for that season. Winning it once is an honor.

Winning it three years in a row is impressive.

Ivan Lendl accomplished this. So did Ilie Nastase. But winning it four years in a row is more impressive. That is what Martina Navratilova did.

In 1986, there were actually two Masters Tour Finals, as the place in the calendar year was changed. Lendl won both of those, and then the 1987 title as well. In all three, he won the finals in straight sets, despite the best-of-five format in those rounds.

Nastase faced much stiffer challenges.

Beginning in 1971, he won three straight titles, defeating American Stan Smith twice in a row and Dutchman Tom Oker once. He won eight sets in those matches, while losing four.

The fact remains, however. Both Lendl and Nastase impressed with these wins in back-to-back-to-back fashion.

Three wins wouldn't be enough to satisfy their female counterpart, Navratilova. She went a bit further, taking the end-of-year Virginia Slims Championships in 1983, 1984, 1985 and 1986. She beat the best-of-the-rest of her generation time and again to prove her master class.

No. 1: Most Consecutive Years with at Least One Title

The most impressive winning streak in tennis has to be the one with the most longevity. Only one run meets that criterion: the most consecutive years with at least one title.

And there certainly is longevity here.

On the men's side, Ivan Lendl went 14 straight years with at least one trophy in his case. Beginning in 1980, when he won seven times, through 1993 when he added three more, he garnered a total of 94 tournament wins.

1982 marked high tide for Lendl. He won 15 tournaments in that season. As late as 1989, however, he took in 10 more, including the Australian Open.

A winning streak of 14 years is now, and perhaps will remain, the most impressive winning streak in men's tennis history.

It is almost no surprise that Martina Navratilova owns the longest run in this ultimate category, too. She took Lendl's 14 years in the limelight and added 50 percent to it. That's right, 21 straight years with at least one title to claim as her own.